1. Technical Field
The present invention relates to a barrel plating apparatus.
2. Description of the Related Art
A process for generally manufacturing chip parts such as varistors, chip inductors, or Multi Layer Ceramic Capacitors (MLCCs) is described as follows.
1) A main material for a ceramic capacitor and a sub material which is an additive are caused to uniformly act on each other and are compounded. 2) The compounded ceramic material is mixed with a polymer binder and a solvent. 3) A slurry mixture is ripened into a stabilized state. 4) A polymer film (polyethylene terephthalate: PET) is coated with a predetermined thickness of the ripened ceramic slurry. 5) Molded tape is dried by passing it through a dry furnace, and 6) a desired capacity design pattern is printed on the tape using a silk screen, and thus internal electrodes are formed. 7) A ceramic sheet is dried in the dry furnace to maintain the paste shape of the printed internal electrodes. 8) The ceramic sheet is formed as multiple layers to obtain a desired capacity value, and 9) a multi-layer ceramic sheet is externally pressed with high pressure to maintain its layered state. 10) A layered ceramic bar is cut in the shape of chips having a predetermined size, and 11) a de-binder operation is performed to remove only binders included in the cut ceramic chips. 12) Chips, the de-binder operation of which has been completed, are heat-processed in a high-temperature electric furnace and are then plastically deformed. 13) The plastically deformed chips are polished so that sharp edges thereof are processed. 14) External electrodes are formed on external portions of the chips so that they are connected to the internal electrodes formed in the chips. 15) The chips, the internal and external electrodes of which have been terminated, are heat-processed, and are then fixed to the surface of the ceramic material. Further, 16) in order to render the external electrodes of the chips solderable, the external surfaces of the chips are plated with nickel and tin. 17) The parts of the chips, the plating of which has been completed, are sorted according to capacity deviation (J, K, M, Z), and the defects of insulation resistances (IR) are sorted. Thereafter, 18) the chip parts are taped using tape and packaged to enable the surface mounting of the parts.
As described above, since soldering cannot be directly performed on external electrodes which have been terminated during a process for manufacturing chip parts, the chip parts are sequentially plated with nickel (Ni) and Tin (Sn) as outermost electrodes so that soldering can be smoothly performed. A plating method used at that time is barrel plating.
Such barrel plating is a method of plating products such as chip parts having small shapes and sizes in bulk at one time, and the method is configured such that, as a barrel container immersed in a barrel plating tank rotates, products are frictionally polished while coming into contact with each other, so that the products come into contact with cathode rods and are plated while current is controlled, and thus considerable brightness occurs on the products.
However, the conventional barrel plating apparatus is problematic in that, while the barrel container rotates for a long period of time, chip parts and media separately gather at different locations in the barrel container, so that mixing efficiency deteriorates, differences in density occur, and the internal resistances of a plurality of cathode rods change to cause variations in current, thus resulting in variations in plating thickness.
Furthermore, since the conventional barrel plating apparatus is problematic in that, when a defect occurs in any one of a plurality of cathode rods coming into direct contact with chip parts, such a defect cannot be easily detected, and in that, when such a defect is neglected, variations in plating thickness become serious.